Kenwood Direct Drive - Oiling the Bearing

snap, crackle and pop
Shoji
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Post by Shoji » 05 Nov 2009 20:28

Hello Caligari. In photograph is actual possible see is grease on spindle shaft of rotor. Prson is may be adding oil but still this model motor series not design for oil. Some time see example of this turntable with oil leakage around under side when such attempt made. This still make much fun for experiment and own enjoyment :D

caligari
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Re: KD-770D Headshell

Post by caligari » 05 Nov 2009 21:11

Chazzer wrote:Please Gentntlemen, Can someone help me locate a original headshell for my KD-770D. I have searched high and low but cannot locate one. In fact I have not even come across another angled headshell that will attach to the tone arm.
Mucho Thanks, Jim
I am looking for one myself. It's really really hard to find. I manage to use an aftermarket headshell that has a pivot point that I can lock the angle. I don't know who made this but I happen to have one around so I have been using that for a while now.

I don't know how to load picture here. I would like to show a picture...

Chazzer
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Post by Chazzer » 06 Nov 2009 00:09

It's down right whacky how many of these KD-770D's I have come across that are missing their original headsell. They have to be some where! Who's hoarding the headshells? Who's hoarding the headshells? :wink:

Hugo
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Post by Hugo » 06 Nov 2009 07:33

Chazzer wrote:It's down right whacky how many of these KD-770D's I have come across that are missing their original headsell. They have to be some where! Who's hoarding the headshells? Who's hoarding the headshells? :wink:
When I bought my KD-770D, the original headshell was missing too.
Shoji wrote:Hello Hugo. Motor plus control is different. Motor series DDM look much same but is different. Motor in model KP-1100 is highest specification of DDM series. KP designation is Japan only model. Other market model mostly KD designation. Please in addition also I send PM for mention of grease.
Sorry - you're correct. Kenwood produced a big range of very similar DD decks, and I was getting confused with the others. The KD-770D is still true quality, though, particularly when a decent external regulated PSU is used to bypass the crude Kenwood circuit.

Regarding the bearing, I may look into having a new bearing sleeve made, which could accommodate a ceramic ball and teflon thrust pad; also sealed to keep the oil in. The end of the original bearing shaft will have to be machined to hold the ball, but that wouldn't be difficult. My only question is how critical is the clearance between the ferrite rotor and the circuit board that sits above the coils? Shoji - do you know this?

Shoji
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Post by Shoji » 06 Nov 2009 11:51

Hello Hugo. Motor design is to give slim profile. Design is for correct cutting of flux lines. Change to air gap will make result of reduced EMF generation and make bad effect for motor. Component change also required for correct function of TA7234 motor driver. Will still perform reduced function. I make recommendation not to make such modification. If must apply modification to bearing then suggestion is for making modification from under side. Plenty ideas applied to design of DDM DL series motor before final production make commence and final design give best performance.

Hugo
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Post by Hugo » 06 Nov 2009 13:03

Thanks. The new bearing housing would be longer, so that the rotor sits at precisely the same height as before, above the circuit board. It is clear that the strong magnetic attraction between the rotor and the motor unit results in much increased drag on the flat ended bearing shaft. I believe that a ceramic ball bearing and teflon thrust pad arrangement would be much more satisfactory.

caligari
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Post by caligari » 08 Nov 2009 14:53

Chazzer wrote:It's down right whacky how many of these KD-770D's I have come across that are missing their original headsell. They have to be some where! Who's hoarding the headshells? Who's hoarding the headshells? :wink:
Obviously I am not one of them because I have to use an alternative, brand unknown.

http://i801.photobucket.com/albums/yy30 ... 1257691705

caligari
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Post by caligari » 11 Nov 2009 00:53

Hugo wrote:
caligari wrote:I can take the motor out and mount it to a different plinth that is more solid and more compact and the run umbilical cords to the control electronics and power supply in a separate enclosure.
You must be reading my mind! This is exactly what I am planning to do, perhaps with an acrylic chassis.
I did exactly that today. Instead of using the Kenwood KD-770D, I used a much cheaper turntable. The JVC QL-A2 that has a plastic plinth but inside has one of the best direct-drive coreless motors by JVC. Sounds excellent! Fun project.

http://i801.photobucket.com/albums/yy30 ... 1257900355

Hugo
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Post by Hugo » 13 Nov 2009 13:30

My KD-770D re-plinth may well incorporate Pete Riggle's VTAF too.

sc_ita
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Post by sc_ita » 14 Nov 2009 23:44

Hallo, I am new to this forum. This is a very interesting thread for me.
I have just purchased a Kenwood KD-770D. It is in the standard form, with original tonearm and PSU. From some first comparisons with my Technics sl1210m5g (which I consider a great deck), it seems to have globally a more "smooth" approach to the music, but it lack somewhat in "speed" and "attach".
I have understood that an unpgrade of the PSU would be more that usefull.
A question: has anyone taken apart the tonearm to tighten the screws at the joint? I think that my tonearm is a little loose (i.e. it has some play).
Bye,
SC

caligari
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Post by caligari » 05 Jun 2010 00:20

Chazzer: "It's down right whacky how many of these KD-770D's I have come across that are missing their original headsell. They have to be some where! Who's hoarding the headshells? Who's hoarding the headshells?"


I recently purchased a headshell from the owner of a Graham Robin tonearm. It appears the Robin headshell is almost identical to the headshell from Kenwood KD-770D. The Robin is sourced from Jelco so I have to assume Jelco also made the arm for Kenwood. Unfortunately Graham has already discontinued the Robin so owner of KD-770D missing headshell has to find one in the used market. Good luck!

Black Stuart
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Post by Black Stuart » 13 Feb 2011 14:32

I know this is a relatively old thread but maybe my post will generate some response.

I knew Hugo form another forum and I don't know why but I never saw this thread.
Now I know why Hugo was not happy with the KD770 - quite literally it is in all important areas a different animal to the KD990 or the KD 7010, this is the second Kenwood I bought.

Stay away from the KD770 - it is the very symbiotic nature of the motor and bearing that make for such a wonderful neutral sound of the 990/7010.

I simply cannot see why anyone would think that any of the Rega arms can compete with the Kenwood arm. It is as caligari says such a well designed arm, far better than any of the Rga or Rega based arms.

Do not touch the bearings on the Kenwood arm they are 'sealed for life' and will be ruined if you tamper with them.

After fruitlessly trying to find suitable PSU caps to replace the Elna ones I have to give up and send the PCB off to Vantage Audio to be repaired.

I have completely modded a Lehman Black Cube phono stage and it benefits from Naked Vishay S102 resistors in the signal path, brilliant little ERSE caps and the o/put caps are BG N. I have also replaced the little yellow Wimas with silver mica caps. Bolted to the box where the arm o/put wires exit they are soldered directly to the B/C PCB - this allows me to use my own unsheilded i/cs - this is game over for me on the vinyl front - now onto digitising all my LPs but that's another story.

farispaul
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Re:

Post by farispaul » 13 Dec 2012 10:17

Black Stuart wrote:I know this is a relatively old thread but maybe my post will generate some response.

I knew Hugo form another forum and I don't know why but I never saw this thread.
Now I know why Hugo was not happy with the KD770 - quite literally it is in all important areas a different animal to the KD990 or the KD 7010, this is the second Kenwood I bought.

Stay away from the KD770 - it is the very symbiotic nature of the motor and bearing that make for such a wonderful neutral sound of the 990/7010.

I simply cannot see why anyone would think that any of the Rega arms can compete with the Kenwood arm. It is as caligari says such a well designed arm, far better than any of the Rga or Rega based arms.

Do not touch the bearings on the Kenwood arm they are 'sealed for life' and will be ruined if you tamper with them.

After fruitlessly trying to find suitable PSU caps to replace the Elna ones I have to give up and send the PCB off to Vantage Audio to be repaired.

I have completely modded a Lehman Black Cube phono stage and it benefits from Naked Vishay S102 resistors in the signal path, brilliant little ERSE caps and the o/put caps are BG N. I have also replaced the little yellow Wimas with silver mica caps. Bolted to the box where the arm o/put wires exit they are soldered directly to the B/C PCB - this allows me to use my own unsheilded i/cs - this is game over for me on the vinyl front - now onto digitising all my LPs but that's another story.
I have one. On the sale listing if anyone interested...

Coffee Phil
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Re:

Post by Coffee Phil » 13 Dec 2012 17:31

Hi Nat,

I'm glad to read that you say it is straightforward. I have had my KD 500 motor open and hacked a fair bit into the electronics but I never messed with the mechanical parts. I converted it into a four speed quartz locked machine. A slip with the scope probe took out the main IC so after that I was committed. As you may expect this project took a long time so if my bearing craps out I'll cry a lot.

So far it is still very smooth. I just hope turning it at 78 RPM or even 80 RPM for Edisons isn't shortening it's life.

Here is a picture of it playing a 78.

[img]17916[/img]

If you have any pictures, or more words on bearing maintence on this machine please do post them.

Phil

nat wrote:Often the spindle is integrated into the rotor of the motor, and you have to figure out how to remove the whole thing. It the motor is on top of the plinth, often there is a decorative cover, but if below, the whole motor must be dropped. On the KD 500 there is a speed sensor that must be loosened and moved out of the way, but otherwise straightforward.
But I don't know the 770 -- have you checked for a service manual?

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Re: Kenwood Direct Drive - Oiling the Bearing

Post by farispaul » 13 Dec 2012 22:11

I meant to say I've the headshell for the 770d, not the whole turntable for sale.